Web-Based Surveys Can Help Track Infection Outbreaks

Action Points

Note that the authors of this study suggest that Internet-based surveys -- increasingly being used by public health officials to investigate infectious disease outbreaks -- are convenient but need careful design and follow-up if they are to be as reliable as telephone surveys.

Internet-based surveys -- increasingly being used by public health officials to investigate infectious disease outbreaks -- are convenient but need careful design and follow-up if they are to be as reliable as telephone surveys, CDC researchers suggested.

Five days after an outbreak of norovirus gastroenteritis among participants in a 475-mile bicycle ride in September 2009, public health officials recruited 204 of the riders for a web-based survey and 93 for a telephone survey, according to John Y. Oh, MD, of the CDC and the Oregon Public Health Division.

The surveys, which were identical, contained 95 questions about food consumption and accommodations during the race, and were expected to take 10 to 15 minutes to complete.

Similar numbers of riders initiated responses to the surveys -- 76% of the Internet group and 84% of the telephone group.

However, fewer of the Internet survey group completed the survey (64% versus 79%, P=0.01), Oh and colleagues reported in the November Emerging Infectious Diseases.

And while 94% of the telephone survey group answered at least 90% of the questions about foods consumed during the race, only 57% of the Internet group did so (P<0.0001).

Significantly more men in the telephone group than in the Internet group completed the survey (79% versus 62%, P=0.03).

More riders 50 years and older in the Internet cohort completed the questionnaire (70% versus 56%, P<0.05).

A total of 18% of both Internet and telephone cohorts were determined to be cases of gastroenteritis.

Camping in the organizer's tents during the race, as opposed to having other accommodations, was significantly associated with illness in the Internet group (35% versus 12%, RR 3, 95% CI 1.4 to 6).

Using the tents, however, was not associated with illness in the telephone group (22% versus 17%, RR 1.3, 95% CI 0.5 to 3.8).

The reasons for this difference were unclear, because similar proportions in the two groups used the organizer's tents. Also, the tents were reassigned at the end of each day, so participants didn't use the same tent each night.

Insufficient power in the telephone survey group could help explain this, according to the researchers.

"Nonetheless, an environmental source of exposure from contaminated tents is biologically plausible, given the low infectious dose of norovirus and its ability to persist on surfaces," they wrote.

Certain lessons can be learned from these findings, the researchers explained.

Reminders sent five days after the original message increased the response rate, and more reminders sent earlier might further increase the response.

The surveys and reminders should specifically request responses from all those invited to participate, not just from those who were ill.

And because the Internet surveys lack the assistance of a telephone prompter who could answer questions and encourage completion of the questionnaire, designing on-line surveys to have mandatory data checks during progression through the questions could help encourage participants to finish.

"Internet survey methods might be more practically suited for relatively shorter, straightforward questionnaires that do not risk respondent fatigue and early termination and do not attempt to assess complex arrays of potential exposures that might require interviewer clarification and assistance," they observed.

They also noted that, although the up-front time and cost of designing high-quality Internet surveys could be higher, once the instrument is in use there would be less public health expense incurred.

There also is a need for ongoing evaluation and validation of the surveys, they noted.

Limitations of the study included possible lack of generalizability of the data to populations with different Internet access and use.

Also, the five-day initial delay in administering the survey may have influenced recall and responses.

The study was supported by the Centers for Disease Control and Prevention's Emerging Infections Program.

Accessibility Statement

At MedPage Today, we are committed to ensuring that individuals with disabilities can access all of the content offered by MedPage Today through our website and other properties. If you are having trouble accessing www.medpagetoday.com, MedPageToday's mobile apps, please email legal@ziffdavis.com for assistance. Please put "ADA Inquiry" in the subject line of your email.